You'll take a line from the external mic preamp into the line input on the rear of the Q10. It almost seems like your confused about preamps. When we talk about using outboard pre's, we're talking about standalone *microphone preamps*. A microphone preamp takes a low level microphone signal and amplifies it to line level. Just because you can attenuate the line in channels on the Aardvark doesn't make them microphone preamps, and I've never heard of anybody using outboard line preamps except (except I guess in high end consumer stereo systems).
The line out of the preamp can be either 1/4" TRS, XLR (both of which would imply balancing) or 1/4" TS (unbalanced). The line ins on the Q10 are balanced 1/4" TRS jacks, so that end of the cable can be 1/4" TRS (balanced) or 1/4" TS (unbalanced).
At any rate, I bet the mic pres on the Q10 are as good as any entry level preamps you'll find, so you might not have to worry so much about pres unless you decide you need some variation. "Nicer preamps" will probably start running in the $300 per channel range, up to $1,500 per channel or more.
Slackmaster 2000